Electric motor operated timer control system



Aug. 16, 1949.

J. w. MCNAIRY 2,479,390

ELECTRIC MOTOR OPERATED TIMER CONTROL SYSTEM Filed July 25, 1948 Inventor.

Jacob W. Mc-Nair His Attorney.

Patented Aug. 16, 1949 I ELECTRIC MOTOR OPERATED TIMER CONTROL SYSTEM Jacob W. McNairy, General Electric New York Westport, Conn, assignor to Company, a corporation of Application July 23, 1948, Serial No. 40,335 3 Claims. (01. 318-452) In control systems wherein an electric timer motor is used to efiect actuation of switches for controlling a series of sequential operations and wherein the circuits for the timer motor are controlled by certain of such switches, diiiiculty may be experienced, especially where slow make and break switches are used, should a switch controlling a circuit for the timer motor dwell in open position and thus stop the timer motor, for should this occur, the mechanism being operated will continue to operate on the particular phase of the cycle through which it was passing at the time the switch opened. Such a situation may arise, for example, in connection with the operation of automatic clothes washing machines wherein there are successive filling, washing, and

for automatic clothes washing machines that I have elected to illustrate and describe my invention. It is to be understood, however, that this is only by way of example and that my invention may be used wherever found applicable.

The object of my invention is to provide an improved system for overcoming the abovereferred to difliculties and for a consideration of novel and my invention, attention is directed to the following specification and to the claims appended thereto.

In the drawing, Fig. 1 is a diagrammatic view of a part of an automatic washing machine control system embodying my invention; and Fig. 2 is a similar view of another such system. Only so much of the control systems are shown as is needed for an understanding of my invention. of the drawing, l indicates an electric driving motor which in the case of an automatic washing machine may be utilized at one time for actuating the washing means and at another time for actuating the means for extracting water from the clothes. In a known type of automatic washing machine, motor i the basket to centrifugally extract water from the clothes. Two electric circuits are provided for and conductor 5, B. The circuit for the extracting operation is through conductor 2, contacts I of the two-position switch 4, conductor 8, contacts of aswitch 9, and conductor ill, to line B. The sets of contacts 3 and l are shown as being bridged by a switch blade H actuated by a rod H, with which is connected an overflow cup i3 provided with a leakage opening I 2a. When overflow cup 13 is full of water, contacts 3 are bridged as shown in the drawing to close the washing circuit for motor I. When cup I3 is empty, contacts 1 are bridged to close the circuit on motor i for the extracting operation. It indicates a spout through which water is supplied to cup ii. The particular control system illustrated is one for use in an automatic clothes washing machine wherein during the washing operation, a pump circulates water continuously from the bottom of the tub of the washing machine to the spin basket, from which it overflows back to the tub. With this arrangement, the washing operation is controlled by overflow of water from the spin go basket. In the present drawing, the arrangement ent to Bariifi 2,432,271,

is indicated only diagrammatically, as the specific arrangement forms no part of my present invention. A washing machine construction of this type and one in connection with which my control system may be used is shown in the pat- December 9, 1947, Liquid overflow control means for washing machines, which patent is assigned to the same assignee as the instant application.

Operation of mechanism to eifect the extraction operation is controlled by a solenoid valve ii, the winding of which is in a circuit from line A through conductor i6, conductor 8, contacts of switch 9, and conductor ill, to line B. To change from a washing operation to an extracting operation, switch 9 is closedby its switch blade I! to efiect operation of solenoid valve l5, and switch 4 is actuated to move its switch blade H from engagement with contacts 3 to engagement with contacts 1. The mechanism controlled by valve I5 is not illustrated as the spe- For an understanding of this invention, it is driven by it are actuated to perform another type of operatIon,-for example, an extracting operation,

I8 indicates 'an electric timer motor. a washing operation, a circuit is closed through the timer motor by way of conductor I8, winding of the timer motor, conductor 28. contacts 2i of a two-position switch 22, conductor 23, contacts 2 of switch 4, and conductor 5 to line B. During an extraction operation, a circuit is closed through timer motor I8 by way of conductor I8, conductor 28, contacts 24 of switch 22, and conductor 25 to line B.

In Fig. 1, the switches are shown as being positioned for a washing operation. To change from washing to extracting, switch -22 is actuated to open contacts 2i and close contacts 24, and switch 8 is moved to closed position. During this change,

the circuit through motor I is initailly closed through contacts 3, but as soon as the extraction operation starts, so that water is no longer supplied to cup I2, the water in the cup leaks from it, whereupon the circuit for motor I is transferred from contacts 3 to contacts I.

Switches 8 and 22 are actuated by cams 26 and 21 driven by timer motor I8; and in this con- .nection, it is to be noted that the switch 22 which controls the timer circuits is actuated by a cam driven by the timer motor. In transferring from.

one circuit to another, where several switches are to be operated, it is diflicult to time the switches so they operate at exactly the same instant; For this reason, it is desirable to operate certain of the switches in advance of others. In the present instance, the switch 22 which controls the timer motor circuits is operated in advance of switch 8, as is indicated by the cam positions in the drawing. With this arrangement, it will be clear that if, when operated, the switch blade of switch 22 should move from engagement with the one set of contacts and should for some reason dwell in an intermediate position between contacts 2i and 24, the timing motor I8 might stop, before it had moved cam 21 far enough to complete the switch movement. As a result, the circuits would remain in the same condition which, in this particular instance, would mean that the washing operation would continue indefinitely.

According to my invention, I overcome this difliculty by utilizing a timer motor which when running will continue to operate on a voltage lower than that of the line (i, e. its normal rated voltage) and which may be capable of starting when such a lower voltage is applied to it and then placing a resistance 28 parallel to switch 22. Resistance 28 is normally short-circuited by switch 22 and is of sumciently high value that normally but very little current passes through it. However, when switch sufhcient current will pass timer motor I8 operating suflicient to eflect complete actuation ot switch 22 so as to insure continuous operation of the mechanism; also, the'timer motor may be such that with partial voltage applied to it, it will start operating. In the case of the usual 115 volt household circuit, I have found the use of a timer motor which will operate or start on voltages of the order of 65 to 80 volts satisfactory; Such motors are known and are available on the open market. Because of the high value of reslstance 28, however, the motor I will not operate through the circuit including contacts '24 and said resistance. a

Assume now a circuit condition wherein switch During 22 is in open position,

through it to keep the for a time at least.

, washing machine or the :motor circuits and in .swhereby when said for. the timer motor. a second the timer motor, a

' period. When the machine is filled for operation,

switch 4 will be actuated by cup is to bring switch blade II into engagement with contacts 3. This closes the one circuit on motor I and cioses the timer motor circuit through contacts M of switch 22. However, should it happen that at this time switch 22 is not closed on contacts 2i, a circuit will be closed on timer motor I8 through resistance 28, thus applying to motor I6 voltage suificlent to start it and eflect actuation of switch 22 to close it on contactsZi. I

In Fig. 2 is shown another control system embodying my invention. In Fig. 2, reference numerals the same as those of Fig. 1 have been applied to corresponding parts. One circuit for motor I (for example the wash circuit) is throlliih a float switch 38 and one side of two-position switch 3i controlled by a cam 22; and another circuit (for example the extractor circuit) is vthrough switch 9 controlled by cam 28, The circuit for valve I5 is through the other side oi switch 3i. One circuit for control motor i8 is through one side of the two-position switch'22; float switch 39, and one side of switch 2i; and another circuit is through the, other side' of switch 22. I resistance 28 is connected iii-parallel to switch 22 and functions in the manner" alreadydescribed in connection with Fig. 1.

A control-system as shown in Fig. 2 is well] adapted for use in controlling an automatic clothes washing machine of the type described in' connection with Fig. 1,.except that instead of the driving motor circuit for washing being under control of water overflow, it is'under control of 'the float switch 38 which closes when the water level in the machine has reached the desired value and opens when value.

In Figs. 1 and 2 the several switches are shown diagrammatically. Any suitable type switch may be used. For cam-actuated switches for use in a system of this type, I prefer to use snap action switches of the column spring type, such as those described in the application of Heber L. Newell,

Serial No. 665,501, filed April 2'7, 1946, and assigned to the same assignee as the instant appli-, cation.

What I claim as new and desire to secureby Letters latent oi the United States is as follows;

1. In a control system for an automatic clothes like, an electric timer motor which will operate when its rated voltage or a voltage substantially lower than its .rated voltage'is applied thereto, a first control circuit control clrcuitfor two-position switch means which in one positioncloses one of said timer other of said timer .ating means driven ating said "switch means, and a resistance in parallel to said switch means through which a circuit is maintained through the timer motor switch means is in open position limited voltage will be timer motor to keep it in operation.

2. In a control system for an automatic clothes washing machine or the like. an electric driving motor, a control circuit for'the driving motor, a switch in said circuit, an electric timer motor As in the arrangement of Fig.1,

the level falls below such another position closes the motor circuits, switch actubythe timer motor for actumaintained on the which will operate when its rated voltage or a voltage substantially lower than its rated voltage is applied thereto, a first control circuit for the timer motor, a second control circuit for the timer motor, a. two-position switch means which in one position closes one of said timer motor circuits and in another position closes the other of said timer motor circuits, switch actuating means driven by the timer motor for actuating said switch and said switch means, and a resistance in parallel to' said switch means through which a. circuit is maintained through the timer motor whereby when said switch means is in open position limited voltage will be maintained on the timer motor to keep it in operation.

3. In a control system for an automatic clothes washing machine or the like, an electric driving motor, a first control circuit for the driving motor, a second control circuit for the driving motor, switches in each of said circuits, an electric timer motor which will operate when its rated voltage or a voltage substantially lower than its rated voltage is applied thereto, a first control circuit for the timer motor, a second control circuit for the timer motor, a two-position switch means which in one position closes one of said timer motor circuits and in another position closes the other of said timer motor circuits, switch actuating means driven by the timer motor for actuating said switches and said switch means, and a resistance in parallel to said switch means through which a circuit is maintained through the timer motor whereby when said switch means is in open position limited voltage will be maintained on the timer motor to keep it in operation.

JACOB W. McNAIRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

